Social entrepreneursenterprising individuals who apply business practices to solving societal problems such as pollution, poor nutrition, and povertyare now 30,000 strong and growing, according to B Lab, a nonprofit organization that certifies these purpose-driven companies. Together, they represent some $40 billion in revenue.

Not surprising, then, that they've caught the attention of venture capitalists such as those at Acumen Fund, a nonprofit that invests in companies that try to alleviate poverty, and Bay Area Equity Fund, which backs businesses aiming to make social or environmental improvements to San Francisco's needier neighborhoods. President Obama has even suggested starting a new government agency to help socially conscious startups gain more access to venture capital.

Back in January, we asked readers and a few members of the social enterprise community to nominate candidates whose trailblazing companies, in operation for at least a year, aimed to turn a profit while tackling social ills.

After the call for nominations ended on Feb. 20, our staff sifted through more than 200 and narrowed the impressive group down to a final 25. To read profiles of the finalists, click on. At the end of the slide show, you can vote for the business you feel holds the most promise, from now until Apr. 27. We'll announce the top five vote-getters on May 1. (Note: All revenues and traffic numbers are self-reported.)